LOS ANGELES (CNN) -- Dr. Conrad Murray, who was Michael Jackson's personal physician, is refusing to testify in the wrongful death lawsuit that the singer's mother filed against concert promoter AEG Live.

If called, he will plead the fifth so as not to incriminate himself, the doctor said in a statement sent to the Jackson family.

Murray has never been questioned under oath about Jackson's death which occurred on his watch.

He did not testify at his trial, where he was found guilty of causing Jackson's death on June 25, 2009, by administering a deadly overdose of sedatives and the surgical anesthetic propofol in what he told police was an attempt to cure the singer's insomnia.

He is serving a four-year sentence but could be out in two.

On Monday, he was supposed to be deposed in the wrongful death suit.

But lawyers for Jackson's mother, Katherine, and her three children called off their jailhouse visit because Murray swore "he would not answer any questions at the deposition or the trial," Jackson lawyer Kevin Boyle told CNN.

He said the Jackson case would not suffer without his testimony.

AEG's lawyer suggests the Jacksons canceled Murray's deposition because his testimony would "destroy" their case.

"They are not interested in the truth," said the lawyer, Marvin Putnam.

Asserting his 'Fifth Amendment privilege'

The cancellation came after Murray's attorney Valerie Wass sent the Jacksons a sworn statement signed by Murray making it clear he would not answer any questions while his involuntary manslaughter conviction in Michael Jackson's death is being appealed.

"Accordingly, if I am called or ordered to testify at deposition or trial in the Katherine Jackson vs AEG wrongful death case, I will be asserting my Fifth Amendment privilege against self-incrimination and refuse to answer any questions," Murray's declaration said.

Jury selection in the civil trial is set to begin April 2 in a Los Angeles County court.

Prince Jackson, the pop star's oldest son, is expected to testify about his father's last days.

Jacksons: Focus back on AEG

The Jackson lawsuit contends that AEG Live is responsible for Jackson's death because it hired and supervised Dr. Murray, who was administering the surgical anesthetic propofol to Jackson each night for a month to induce sleep as he prepared for a series of concerts organized by AEG Live.

A jury found Dr. Murray guilty of involuntary manslaughter after hearing testimony that he violated medical standards in his treatment of Jackson.

"Dr. Murray's choice to keep quiet puts the focus back on the company -- AEG -- that hired Dr. Murray and agreed to pay him over $1.5 million a year, and provide Murray with a large house and drivers and other perks, to make sure that the company's biggest asset, Michael Jackson, made it to the shows on time, no matter what," Boyle, the Jacksons' lawyer said.

The judge ruled last month that Jackson lawyers could question Murray at the Los Angeles County jail, where he is serving his prison sentence.

AEG: Testimony destroys Jacksons' claim

"The Jacksons told the world that they wanted Dr. Murray's deposition, and then when the Court gave it to them, they canceled it," Putnam, the AEG lawyer, told CNN on Sunday.

"They have had all of their claims dismissed except negligent hiring, and they don't want Dr. Murray to be deposed because he will tell them what he already told the police -- that he worked for Michael Jackson; that Michael Jackson, not AEG, was his employer; and that Michael Jackson personally invited him to join the 'This is It' tour long before anyone at AEG had even heard of him. The Jacksons canceled the deposition because that testimony destroys the only claim they have left. They are not interested in the truth."

Back and forth

The Jacksons' lawyer argued, in response to Putnam's comment, that AEG was not interested in having Murray take the stand in the trial.

"AEG did not even try to get Dr. Murray to talk," Boyle said. "AEG is simply not telling the truth. AEG can't run from the fact that they hired the man who is in jail for killing the greatest entertainer the world has ever known."

Wass, who unsuccessfully objected to the deposition, said she advised Murray to invoke his Fifth Amendment right to not answer questions because of his appeal. The appeal brief is expected to be filed next week.

Jacksons plan to use e-mails

Jackson died two weeks before his "This Is It" comeback concerts, organized by AEG Live, were to have debuted in London in the summer of 2009.

E-mails the Jackson's plan to use in their case suggested that the promoter was worried about Jackson's missed rehearsals and they sought Murray's help in getting him ready.

Prince, Paris and Blanket Jackson and their grandmother contend that AEG Live's pressure on Murray to have Jackson ready for daily rehearsals despite his fragile health led to his death from the propofol overdose.

A cornerstone of the Jacksons' case is an e-mail AEG Live Co-CEO Paul Gongaware wrote 11 days before Jackson's death.

The e-mail to show director Kenny Ortega addressed concerns that Murray had kept Jackson from a rehearsal the day before: "We want to remind (Murray) that it is AEG, not MJ, who is paying his salary. We want to remind him what is expected of him."

Jackson lawyers, calling it a "smoking gun," argue the e-mail is evidence that AEG Live used Murray's fear of losing his $150,000-a-month job as Jackson's personal physician to pressure him to have Jackson ready for rehearsals despite his fragile health.

Billions at stake

The lawsuit seeks a judgment against AEG Live equal to the money Jackson would have earned over the course of his remaining lifetime if he had not died.

If AEG Live is found liable, it could cost the company several billion dollars, according to estimates of Jackson's income potential.

AEG Live is a subsidiary of AEG, a global entertainment company that was recently for sale with an $8 billion asking price.